This is a longitudinal, observational study, which does not include any intervention. There are three study groups. The first group consists of BLSA participants without known coronary disease; the second consists of individuals with a coronary artery calcium score less than the 25th percentile for their age and gender; the third group consists of individuals with premature coronary artery disease (diagnosis made at age <60 in females and <50 in males) or with a coronary calcium score which is greater than the 50th percentile for their age and gender. Participants in the second and third group listed above are recruited from the Johns Hopkins Medical Institutions. Recruitment has been completed and the longitudinal portion of the study is ongoing with nearly one-half of all second visits completed. Analysis of the first visits is being conducted to assess cross sectional findings which can then be expanded to a longitudinal analysis once all second visits are completed. The future analytic plan: Construct z-scores for relevant variables based on: o All the data both overall and age adjusted o The normal group (BLSA participants) both overall and age adjusted Conduct a principal components analysis on the various sets of z-scores to uncover any patterns among the variables Try to find out if the z-scores cluster in any way a discriminant analysis might be an appropriate way to approach this issue (or cluster analysis) Identify BLSA participants with good arterial aging based on single variables and on groups of variables. Find subjects in other groups who have similar profiles on the selected variables.